Learn Hardcore Croatian: Moram priznati da sam večeras umoran. - I have to admit that I am tired tonight.

moram is 1st person singular (I must), so ja (I) is understood.
You would only add ja for emphasis or contrast, e.g. Ja moram priznati… = I have to admit (as opposed to someone else).

So Moram priznati… naturally means “I have to admit…” without saying ja.

What exactly does moram mean, and how is it different from trebam?

Moram is the 1st person singular of morati and usually means “I must / I have to” (obligation).

Moram priznati = I must / I have to admit.
trebam (from trebati) is closer to “I need”, especially with nouns:
- Trebam pomoć. = I need help.

In everyday speech people sometimes say trebam + infinitive (Trebam otići = I need to go), but moram + infinitive is the standard way to say must / have to do something.

Why is it priznati (infinitive) and not priznajem (present tense) after moram?

After moram you use the infinitive, just like in English you say “have to admit”, not “have to admitting”.

Moram priznati = I must / have to admit.
Priznajem on its own would be “I admit” (present tense, no “must”).

So:

Priznajem da sam večeras umoran. = I admit I am tired tonight.
Moram priznati da sam večeras umoran. = I must admit I am tired tonight.

What does da do in this sentence? Is it the same as English “that”?

Yes. In this sentence da is a conjunction meaning “that” introducing a subordinate clause.

Moram priznati da… = I must admit that…
The whole part da sam večeras umoran is the thing you are admitting.

Don’t confuse this da with the colloquial “da” meaning “yes”; here it’s just the conjunction “that.”

Why is it da sam večeras umoran and not da večeras sam umoran?

The short form sam (from biti = “to be”) is a clitic. In Croatian, clitics normally stand in second position in the clause.

In the clause da sam večeras umoran:

da = first element
sam = clitic in second position
večeras umoran = the rest

That’s why da sam večeras umoran is correct, and da večeras sam umoran sounds unnatural. In a main clause without da, however, you can say Večeras sam umoran (“Tonight I am tired”).

Could I say Moram da priznam instead of Moram priznati?

This is a subtle regional / standard-language issue.

In standard Croatian, the usual and preferred form is moram priznati (modal verb + infinitive).
Moram da priznam is typical for Serbian (and common in Bosnian and Montenegrin).

Croatian speakers will understand Moram da priznam, but in Croatia it sounds non‑standard or “Serbian‑like.” If you’re aiming for standard Croatian, use Moram priznati.

What exactly does večeras mean, and how is it different from večer, navečer, etc.?

Večeras is an adverb meaning “this evening / tonight” (the specific upcoming or current evening).

večer is a noun: evening.
- Ove večeri = this evening (more formal / written style).
navečer / večerom = in the evening, in the evenings (more general, habitual):
- Navečer čitam. = I read in the evening / evenings.

In your sentence, večeras clearly means tonight / this evening.

Why is it umoran and not umorna or umorno?

The adjective umoran (tired) must agree with the gender and number of the subject.

Here the subject is implied ja (I), and we normally assume the speaker is male, so:
- umoran = masculine singular.
  If the speaker is female, she would say:
Moram priznati da sam večeras umorna.

Other forms:

umorno = neuter singular (e.g. Dijete je umorno. = The child is tired).

So the form of umoran changes with who is tired.

Can I change the word order to Moram priznati, večeras sam umoran?

Yes, that’s possible and natural, and it slightly changes the flow.

Moram priznati da sam večeras umoran.
- One complex sentence: “I must admit that I am tired tonight.”
Moram priznati, večeras sam umoran.
- Feels more like: “I must admit, I’m tired tonight.” (two closely linked clauses, spoken-style).

Both are fine; the version with da is a bit more explicitly structured as one sentence.

How would this sentence change if the speaker were female or if it were plural?

Only the verb forms and adjective endings change; the structure stays the same.

Female speaker (singular):
- Moram priznati da sam večeras umorna.
  (“umorna” = feminine singular)
Group including at least one male (we):
- Moramo priznati da smo večeras umorni.
  (“moramo” = we must, “smo” = we are, “umorni” = masculine plural / mixed group)
All‑female group (we):
- Moramo priznati da smo večeras umorne.
  (“umorne” = feminine plural)
Formal “you” (Vi):
- Morate priznati da ste večeras umorni / umorne.
  (masc. / mixed vs. all‑female group)

The pattern: moram/moramo/morate and sam/smo/ste change with person/number, and the adjective (umoran) agrees in gender and number with the subject.